Abstract: A laser rangefinder for clouds, fog, haze and precipitation including an erbium doped laser transmitter, a germanium photodiode monitor and a germanium avalanche photodiode detector. The germanium avalanche photodiode and an amplifier module is positioned at the focus of a parabolic reflector. The transmitter transmits light in a waveband with an optical center at 1.54 microns and is eye safe. A periscope system aligns the outgoing pulse with the returning light to reduce parallax.To reduce alignment problems when shifts in wavelengths occur, an optical circuit with only reflecting surfaces can be employed.To increase the efficiency of the laser transmitter, the clamps utilized to position the laser rod within the cavity are formed of the same material as the laser rod and the pump light reflector is a second surface mirror with a quartz substrate coated in succession with silver, copper and black paint.